In recent years, reduction of weights of various apparatuses is desired, and reduction of weights of resin molded articles forming parts of the apparatuses is also desired. One example of a method for reducing the weight of a resin molded article is a method of foaming a resin through a molding method including a core-back step, for example. A molded article made of foamed resin, i.e., a foamed resin molded article, has a large number of pores therein. Thus, such a molded article has a lower density and a smaller weight than a solid resin molded article not containing bubbles.
Meanwhile, there is a resin molded article integrally provided with a mounting section for allowing a separate member to be fixed to the resin molded article by means of a tapping screw or the like, for example. The tapping screw is screwed to the mounting section, thereby being fixed to the resin molded article. The separate member is fixed to the resin molded article through the tapping screw.
A relatively large force acts on the mounting section of this kind, when the mounting section is screwed with the tapping screw. Thus, the mounting section is required to have a certain degree of mounting strength. However, there is problem in that, although the foamed resin molded article mentioned above has a large number of pores and thus is effective for weight reduction, the foamed resin molded article is inferior in mounting strength due to the pores, compared with a solid resin molded article.
As a method for improving the mounting strength of amounting section by suppressing resin foaming in the mounting section while realizing weight reduction by causing sufficient resin foaming in a base body in a foamed resin molded article, there is a technique disclosed in Japanese Laid-Open Patent Publication No. 2002-225058, for example. In Japanese Laid-Open Patent Publication No. 2002-225058, the entirety of the mounting section is made thin, whereby the resin material in the mounting section is hardened by the mold surface before a core-back step, so as to suppress resin foaming. Thus, the entirety of the mounting section is formed as a dense resin section, so as to improve the mounting strength of the mounting section.
However, with the technique disclosed in Japanese Laid-Open Patent Publication No. 2002-225058, the entirety of the mounting section can be made as a dense resin section having suppressed resin foaming, whereas the thickness of the entirety of the mounting section is reduced, and thus, the mounting strength of the portion to be screwed with a tapping screw fails to be sufficiently improved.
The present invention has been made in consideration of the circumstances described above. An object of the present invention is to provide a foamed resin molded article integrally having a mounting section formed as a dense resin section having suppressed resin foaming, the mounting section having sufficiently improved mounting strength.
A foamed resin molded article, of the present invention, solving the problem described above includes: a base body; and a mounting section formed integrally with the base body and protruding from the base body, wherein the mounting section includes: a body section having a mounting hole allowing a counterpart member to be inserted therein; and a leg section having one end thereof continuous with the body section and the other end thereof continuous with the base body, and a thickness of a portion at the base body side of the leg section is smaller than a thickness of the body section.
A foamed resin molded article of the present invention includes: a base body; and a mounting section protruding from the base body. The mounting section includes: a body section having a mounting hole allowing a counterpart member, such as a tapping screw, to be inserted therein; and a leg section located between the body section and the base body. The leg section has one end thereof continuous with the body section and the other end thereof continuous with the base body. The thickness of a portion at the base body side of the leg section continuous with the base body is smaller than the thickness of the body section.
For example, when molding employing a foamed resin molding method including a core-back step is performed, the resin material of the portion at the base body side of the leg section, the portion being made thin, is cooled to be hardened by the mold surface before the core-back step. Since the resin material of the portion at the base body side of the leg section is hardened before the core-back step, internal pressure decrease in the cavity of the portion for molding the body section is suppressed and resin foaming in the cavity is sufficiently suppressed in the core-back step. That is, by making thin the portion at the base body side of the leg section in the mounting section, resin foaming in the body section is suppressed without making thin the body section into which the counterpart member is inserted. Therefore, the body section required to have improved mounting strength becomes a dense resin section having suppressed resin foaming, without making the thickness of the body section small.
Therefore, the foamed resin molded article of the present invention realizes a foamed resin molded article integrally having amounting section formed as a dense resin section having suppressed resin foaming, the mounting section having sufficiently improved mounting strength.
Hereinafter, a preferable embodiment of a foamed resin molded article according to the present invention is described with reference to FIG. 1 to FIG. 4. The accompanying drawings used for description are only schematic, and the shapes, relative positional relationships, size relationships, and the like of parts are not necessarily drawn to scale. Unless otherwise specified, a numerical range “x to y” described herein includes a lower limit x and an upper limit y. The upper limit value and the lower limit value as well as numerical values described in the embodiment are optionally combined to provide new numerical ranges. A numerical value optionally selected from these numerical ranges may be used as the numerical value of the upper or lower limit.
Matters required for carrying out the present invention other than matters specifically mentioned herein are understood to be design matters, for a person skilled in the art, based on conventional art in the relevant field. The present invention is carried out on the basis of the contents described herein and common technical knowledge in the relevant field.